1. Field of the Invention
The present invention relates to a human phantom apparatus, a finger phantom apparatus, an apparatus for measuring a characteristic of an antenna using the phantom apparatus, an antenna apparatus, and a radio communication apparatus with the antenna apparatus. In particular, the present invention relates to a human phantom apparatus and a finger phantom apparatus which are used upon measuring a characteristic of an antenna apparatus, an apparatus for measuring a characteristic of an antenna apparatus using the same phantom apparatus, an antenna apparatus constituted based on measurement results of the apparatus for measuring the characteristic of the antenna apparatus, and a radio communication apparatus using the antenna apparatus.
2. Description of the Related Art
In recent years, mobile communication systems, each using a radio communication apparatus such as a mobile phone or the like have been rapidly developed. Generally, the mobile phone is used in the vicinity of a human body, and therefore, it is important to highly accurately measure characteristics of an antenna of the mobile phone, in such a state that the mobile phone is attached to the human body. A conventional measurement of the characteristics of the antenna of the mobile phone has the following disadvantages. Since it has been difficult for a human subject to maintain his or her attitude, reproducibility is deteriorated. Due to great differences among human subjects, it is difficult to relatively compare measurement results with each other. For these reasons, the characteristics of the antenna of the mobile phone have been conventionally measured using a human phantom apparatus as disclosed in, for example, a first patent document of Japanese patent laid-open publication No. JP-P2000-082333-A, and a second patent document of Japanese patent laid-open publication No. JP-P2002-107396-A.
According to the first patent document, for example, in order to provide a composite dielectric capable of mass-producing solid biological phantoms in short time at a lower manufacturing cost, and having uniformly stable electric characteristics, the composite dielectric used for a solid biological phantom is characterized by containing thermosetting resin of 40 to 90 volume % and electrically conductive powder of 10 to 60 volume % (100 volume % in all).
According to the second patent document, for example, in order to measure the change in the characteristics due to a positional relationship between the antenna attached with the mobile phone and the human body or an ear, in particular, with higher accuracy, there is provided a human phantom apparatus that is constructed by a head section including ear sections, a body section, an arm section, a left hand section, and a moving means, and the human phantom is characterized by allowing the arm section to move by the moving means. The second patent document particularly provides the human phantom apparatus having an attitude for holding the mobile phone on the ear of the human phantom apparatus.
The mobile phone is used as a conventional telephone, and further, the mobile phone is also used as a data terminal for transmitting and receiving E-mails and viewing web pages using WWW (Word Wide Web). The frequency increases of using the mobile phone in a user's attitude of holding the mobile phone by his hand in front of his chest. This attitude is referred to as a PDA (Personal Digital Assistance) attitude hereinafter. In order to establish a higher quality of telephone speech communication quality of the mobile phone even in these circumstances, it is necessary to measure the characteristics of the antenna of the mobile phone with higher accuracy in accordance with the positional relationship between the antenna and the human body.
As disclosed by the second patent document, the conventional human phantom apparatus simulates an attitude in telephone speech communication of holding the mobile phone near the ear on the side of the head section, and is unable to measure the characteristics of the antenna in a PDA attitude. In the PDA attitude, the distance between the antenna of the mobile phone and the human body is larger than that that in the conventional attitude of the telephone speech communication. For this reason, it is disadvantageously difficult to highly accurately measure the characteristics of the antenna using the human phantom apparatus different from an actual human body in shapes of sections such as a shoulder, a chest, and an arm, in such a state that a radio wave radiated from a portable radio communication apparatus held in the PDA attitude is reflected and absorbed by the human phantom apparatus.
In addition, since the human phantom apparatus includes a solid material such as composite dielectric or the like, it is disadvantageously difficult to highly accurately simulate a state of the adhesion between fingers and the mobile phone, in such a state that the human phantom apparatus holds the mobile phone. The electric characteristics of the human body change according to the radio frequency being used. In order to deal with this change, it is necessary to manufacture the human phantom apparatus by re-adjusting the composition ratio of the solid materials according to the radio frequency band. As a result, the manufacturing cost disadvantageously increases.
Further, there has been desired a radio communication apparatus that includes at least two antennas, that performs diversity reception, and that can receive radio signals satisfactorily at levels larger than those of the prior art.